Custom Domains on Google Apps Script

It may have occurred to you that when deploying a Google Apps Script web app, the URL spewn forth looks rather long and unattractive:

https://script.google.com/macros/s/*mashes keyboard*/exec

And that it would be a lot nicer to have something more succinct like:

https://mysite.com/thing

Well, this has indeed troubled and racked the minds of many a stackoverflow poster trying to circumvent Google’s top-notch cross-domain prevention skills… until now…

It turns out that the solution to hosting Google Apps Script web apps on custom domains has been under our noses for all this time. The secret sauce lies in the setXFrameOptionsMode method in the HtmlService class. It takes an enum of one of two values: DEFAULTor ALLOWALL. What we want to do is to set this to ALLOWALL.